hwmon: ina209: move binding docs to proper place

The I2C dir is not for I2C client devices! Move it to the proper folder.

Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Acked-by: Guenter Roeck <linux@roeck-us.net>

Documentation/devicetree/bindings/hwmon/ina209.txt

@@ -0,0 +1,18 @@
+ina209 properties
+
+Required properties:
+- compatible: Must be "ti,ina209"
+- reg: I2C address
+
+Optional properties:
+
+- shunt-resistor
+	Shunt resistor value in micro-Ohm
+
+Example:
+
+temp-sensor@4c {
+	compatible = "ti,ina209";
+	reg = <0x4c>;
+	shunt-resistor = <5000>;
+};